The D.C. Perinatal Study is a case-control study designed to elucidate the factors associated with the delivery of a low birth weight infant to resident mothers in the District of Columbia. The study "cases" are low birth weight infants (Less than 2500 grams) born in participating hospitals. "Controls" are selected as the next race matched normal weight infant (= Less than 2500 grams) delivered at the same hospital. The mothers of the cases and controls are being interviewed on the postpartum ward, with data verification obtained through abstraction of medical records. Where possible, prenatal information is being verified by using the prenatal information which is attached to the hospital medical record. However, if the hospital medical record does not contain adequate prenatal information arrangements are being made to abstract this information from private and public physician's offices where care was received. Data collection began February 1, 1984, and will continue until January 31, 1985. The data is being collected by SRA Technologies, Inc. of Arlington, Virginia.